Mass flow meter manufacturer Bronkhurst High-Tech has developed a new, directly driven control valve for gas flow control up to 200 bar - the first without a Vary-P mechanism.
The company says this development makes mass flow controllers fitted with this valve even more compact, offering even faster control.
Previously these units were developed with a Vary-P mechanism. Bronkhorst introduced Vary-P control valves in 1985 for controlling high-pressure gas flow with high pressure differences of up to 400 bar – this was later extended to 700 bar.
The company said, “The control valves – usually integrated in a mass flow controller (F-230 series) are a more compact and much cheaper alternative to flow meters, which are combined with valves that are controlled pneumatically or using a servomotor. For controlling process pressure, Vary-P valves are often also applied in conjunction with Bronkhorst pressure meters. The Vary-P valve comprises a flow control section, along with a mechanism that keeps the differential pressure over this valve at a constant approximately six bar. As a result, the pressure at the inlet and outlet of the mass flow or pressure controller may vary without affecting the control performance.”